The invention relates to a foldable binocular and the blank for forming the binocular.
Several binoculars of this type are known in the prior art and are made of a relatively thin semi-rigid material, such as cardboard. When folded, they are light in weight and compact and suited for taking to sporting events, concerts etc.
One disadvantage of some of the prior art binoculars of this type is that, when folded, the lenses, especialy the larger convex objective lenses, are unprotected and may be scratched when carried in pocket or purse. This disadvantage is overcome in U.S. Pat. Nos. 4,239,328 and 4,478,498 by providing a cardboard sleeve or case in which to store the folded binocular when not in use. However, this solution is not entirely satisfactory since the case must be stored when the binocular is being used.
In U.S. Pat. No. 4,013,341, the lens elements of the binocular are retracted before folding in order to protect them from scratching. However, they must be pulled out by tabs when the binocular is unfolded. This is awkward.
In U.S. Pat. No. 4,443,071, the lenses fold inwardly when the binocular is in a folded state and thus are protected. However, the arrangement is such that, when the binocular is to be used, the various side flaps must be folded individually to reassemble the binocular as one would assemble a box. Then the flaps must be unfolded in order to disassemble the binocular. This is very inconvenient. Several of the fold lines must be folded in reverse during assembly and disassembly, thus weakening the cardboard material.
It is an object of the invention to provide a foldable binocular wherein the lenses are protected when the binocular is in the folded state.
It is a further object to provide a foldable binocular which may be partly disassembled to obtain access to the inner surfaces of the lenses for cleaning, if necessary.